We collect wait times at every Disney theme park every day. When the data warrants a change to the crowd calendar, we do it. Our philosophy is that it is better to have accurate information than to keep things the same purely for consistency's sake. We understand the work that it takes plan out an itinerary so believe us when we say we only make a change when we really feel it is necessary.
You can track the days of your trip to get notified if something changes. If you find that the calendar has changed for the dates of your trip you should review your plans but don't be too quick to make changes. Usually, the changes will be minor enough that it isn't worth it. In our opinion, unless the crowd index changes by more than a single level, stand pat.